Rotatable shaft

ABSTRACT

An antenna rotator, hollow, drive shaft including a clamping member by which a round tubular antenna mast is securely held therein is described. The hollow shaft is mounted as part of a rotating device which provides relative rotational movement between the shaft and a housing.

United States Patent Inventors Neil Worrafl Burwell Moorestown; Franklin Roosevelt Di Meo, Woodbury, both of, NJ. App]. No. 809,662 Filed Mar. 24, 1969 Patented July 27, 1971 Assignee RCA Corporation ROTATABLE SHAFT 6 Claims, 5 Drawing Figs.

US. Cl 248/43, 287/52.07 Int. C1 1-101q 1/12 Field oIScarch 287/52,

[56] References Cited UNITED STATES PATENTS 2,498,957 2/1950 Jordan 343/766 2,951,547 9/1960 Lawrence 306/15 X 3,245,642 4/1966 Dicke 248/45 X FOREIGN PATENTS 157,753 1/1905 Germany 306/1.5 43,854 4/1918 Sweden 306/1.5 1,558,373 1/1969 France 285/199 Primary Examiner-Thomas F. Callaghan Assistant Examiner-Andrew V. Kundrat Attorney-Edward J. Norton ABSTRACT: An antenna rotator, hollow, drive shaft including a clamping member by which a round tubular antenna mast is securely held therein is described. The hollow shaft is mounted as part of a rotating device which provides relative rotational movement between the shaft and a housing.

ROTATABLE SHAFT BACKGROUND OF THE INVENTION I THis invention relates to shaft-securing means and more particularly to an improved rotatable shaft adapted to provide a more secure clamping of a second shaft adjacent thereto.

It is often desirable, for example, where radio and television stations are located in different directions relative to the receivers and where the antennas used are directional antennas, to have an antenna rotator system which rotates the directional antenna to align the antenna with the desired radio or television station. Antenna rotators have become widely used and known for this purpose. An antenna rotator system includes a remote control unit located near the radio or television set, an antenna rotator unit located near the roof of a dwelling, for example, and connecting wires therebetween. The remote control unit functions to supply both power and control signals by means of the connecting wires to the rotator unit which actually rotates the antenna. A typical antenna rotator unit includes an electric motor, a power train and a hollow drive shaft. The electric motor and the power train are located in a waterproof housing, The housing is rigidly fixed to the dwelling and the hollow drive shaft provides rotational movement relative to the housing and the dwelling which are fixed. An antenna support mast is passed through the hollow shaft and is fixed by some means to the hollow shaft. which is rotatable relative to the housing. It is very important therefore for proper operation of the antenna rotator system that the means for holding the rotatable shaft to the antenna mast passed therein be always axially and horizontally secured. Also, since these antenna rotator units as mentioned are usually located near rooftops or other such hard to reach high points, it is imperative that such holding means continue to rigidly secure the antenna mast to the rotatable hollow drive shaft. Conventional rotatable hollow shafts used with antenna rotators are generally tubular in construction with an inner circular diameter and outer circular diameter. The mast is likewise circular and the diameter of the mast or shaft to be placed in the hollow shaft of the housing is smaller than the inner circular diameter of the rotatable hollow shaft. Since the mast is circular and the inner diameter of the rotatable hollow shaft of the housing is circular, the mast tends to roll about the inner circular diameter of the hollow shaft making it difficult to rigidly fix the circular mast thereto.

Also, in many cases, the inner diameter of the hollow shaft near the center of the hollow shaft is smaller than the inner diameter at the ends of the hollow shaft. .This condition is a result of a method used in constructing the hollow shaft. In this method of construction, a pair of mandrels are placed such that one is inserted into the molding from one end of the molding toward the center and the other is inserted into the molding from the other end toward the center. Each'of the mandrels has one diameter which is located near the center of the molding that is smaller than the ends, and the diameter tapers from the one end of the mandrel to the other end, This arrangement is provided to enable withdrawal of the mandrels after molding. The overall result is that the inner diameter after molding is smaller at the center and gradually tapers to a larger diameter at the ends of the hollow shaft. The inside surface of the hollow shaft therefore assumes a type of bow shape when observing the shaft along the longitudinal length. When trying to rigidly fix a relatively straight antenna mast to the shaft having a bowed inner wall, a rigid connection is not possible without bending the mast at the center and/or distorting the hollow shaft.

Conventional masts are clamped to the hollow shaft by means of U-bolt clamps with the bottom-rounded end of the U-bolt about the outer circular end wall of the hollow shaft or about the circular mast and are not rotationally fixed or held tightly to both hollow shaft and mast. The clamps are drawn up against the mast so as to secure the mast to the hollow shaft. As the driven hollow shaft rotates, the clamps tend to rotationally slip as the round end of the U-bolt slips-on the round circular hollow shaft or antenna mast, and consequently, permanent'securing of the mast to the housing is impaired.

It is a first object of the present invention to provide an im proved shaft for securing a second shaft thereto using a clamp.

It is another object of the present invention to provide an improved drive shaft for use in combination with an antenna rotator unit that will more securely hold an antenna mast to the drive shaft of the antenna rotator.

Briefly, these and other objects of the present invention are accomplished by an improved shaft for securing another shaft thereto bya clamp located at a point along the length of the securing shaft. The securing shaft has a V-shaped groove in the inner surface along the longitudinal dimension thereof and has at least one boss on the outside surface thereof positioned so as to be a continuance of that portion of the securing shaft including the V-shaped groove. The boss has a groove therein adapted to receive a portion of the clamp.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the following drawings in which:

FIG. 1 is an elevational view of an antenna rotator having a portion thereof broken away so asto illustrate the placement of the hollow shaft,

FIG. 2 is an end view ofa clamp used in accordance with the present invention,

FIG. 3 is a side view of the hollow shaft in accordance with the present invention,

FIG. 4 is an end view of the hollow shaft shown in FIG. 3, and I FIG. 5 is an end and clamp. I

Referring to FIGS. 1 and 3, there is shown an antenna rotator 10. The antenna rotator is made up of the housing 11, an electric motor. 12, a gear train means 13 and a hollow shaft 15. The electric motor 12 is coupled to the hollow shaft 15 by the gear train means 13. The hollow shaft 15 passes through the view of the assembled hollow shaft mast .housing 11 and is rotatably mounted to the housing 11 using slip rings between the housing 11 and grooves 15b and 15c. A lip 15e is molded for retaining a protective cover placed in groove 1511. At the extreme longitudinal ends a portion of the hollow shaft 15 is removed leaving only extended portions 23 and 25. These extended portions 23 and 25 of the hollow shaft 15 are used to clamp to the antenna mast 20 with part of the clamps 27 and 28 adjacent to the respective extended portions 23 and 25 and part of the clamp 27 and 28 adjacent the mast 20. The antenna mast 20 is passed through the hollow shaft 15 and is fixed to the extended portion by the pair of mast clamp assemblies 27 and 28.

Referring to FIG. 2, the mast clamp assemblies 27 and 28 each comprise a modified form of a U-bolt 31, a retaining clamp bar 32, nuts 33, 34 and washers 35, 36. The bolt, as shown in FIG. 2, differs from the conventional U-bolt structure in that the region of the bolt between the threaded ends which are parallel to each other is not rounded but rather is in the shape of a V with two straight legs of the v extending from the center of the bolt or at the halfway point between the threaded ends. The V-shape extends away from the threaded ends of the bolt. The bolt 31 has sharp bends at three points, one at the center between the threaded ends and one equally spaced on either side of the center bend. The bolt 31 has a series of straight line sections between bent portions and between the bent portion and the threaded ends shown in FIG.

V. The V-shaped portion of bar 32 has a plurality of teeth 32c therein. The retaining clamp bar 32 is arranged relative to the vertex of the V of the bolt 31 so that the vertex of the V of the bolt is directly opposed to the vertex of the V of the clamp bar 32 with both V's pointing in a direction away from each other. The mast clamp assemblies 27, 28 are clamped to the rotatable hollow drive shaft as will be explained.

Referring now to FIGS. 3 and 4 the hollow drive shaft 15 is generally a circular tubular member with a circumferential gear 15a molded therewith at one point along the outer circular surface of the shaft 15. The gear 15a couples to the gear train 13 to provide rotation thereof. The inner surface 38 of the hollow shaft 15 is generally circular in cross section except that along a portion of the inner circumference of the shaft 15 where the mast is to be clamped there are two straight portions 38a, 38b which form a V or a V-shaped groove 40. The straight portions 38a, 38b and the V-shaped groove 40 therefrom extend in a straight line the entire longitudinal length of the inner surface 38 including that at the extreme end portions 23 and 25 of the shaft 15, as shown in the dashed lines of FIG. 3. The groove 40 can be formed by the mandrels, not shown, placed in the molding being so shaped and positioned as to form the shaft 15. At either extended portion 23 and 25 of the shaft 15 is a boss 41 and 42 extending out from the outer surface of the hollow shaft 15. The bossings 41, 42 are located on the outer surface of that portion of the hollow drive shaft 15 where the inner V-shaped groove 40 is located. Each boss 41, 42 has a transverse groove (48, 49) extending transverse to the lengthwise axis of the hollow shaft 15. The depth of the groove 48, 49 varies as shown by the dashed line 48 in P16. 4 wherein the middle portion of the groove opposite the vertex of the V-shaped groove 40 on the inner surface has a depth that is less than thatat the end portions of the groove so as to form a groove therein in each boss 41, 42 that is adaptable to receive the V of the bolt 31 of the clamp assemblies 27, 28, and wherein the V-shape formed in the bossings 41, 42 is approximately parallel to the inner V shaped groove 40 in the inner surface 38 of the shaft 15.

Referring to FIG. 1, the motor 12 and gear train 13 are mounted within the housing 11 and, in installation of the rotator, the housing is fixed to the dwelling or antenna tower. A-

common method of fixing the housing 11 to a dwelling is by clamping the housing 11 to a second mast 70, which in turn is mounted, for example, using a chimney mount to a chimney or to an outside wall using a wall mount.

The mast 20 to which an antenna is mounted is passed through the hollow shaft 15 and is clamped by the modified clamp assemblies 27 and 28 wherein the straight legs of the V of the modified U-bolt 31 fit into grooves 48 and 49 of the boss 41, 42, and the V-shaped retaining clamp bar 32 is drawn up so that the V of the groove 40 opposes the V in the retaining bar 32. P10. 5 shows this clamping arrangement. By this arrangement of clamping the mast to the hollow shaft, the mast is drawn up tightly against the V-shaped groove 40 in the hollow shaft 15 so as to prevent the mast,20 from rolling or otherwise turning in the hollow shaft 15. Since the modified U-bolt has straight legs forming a V at the center and is fitted into a groove adapted to receive this V-shape, the clamp will not rotate in its position when the nuts 33, 34 draw the clamp bar 32 against the mast 20.

1n the manner described above, an improved antenna rotator is provided which is free from rotational and axial slippage of the mast relative to the hollow shaft and having a clamping arrangement that will remain secure even after long periods of rotator usage without servicing dueto the elimination of unwanted rolling motions.

We claim:

1. 'A shaft for improved securing thereto of a second round I tubular shaft by means of at least one V-shaped clamp at a V-shaped groove in the inner surface thereof extendin along the entire ongitudinal dimension of said first-mentione shaft,

and further including a boss located at a clamping point on the outside surface thereof forming an axial continuance of that portion of said first-mentioned shaft having said groove, said boss having a groove transverse to said longitudinal dimension which is adapted to receive the V-shaped portion of said bolt, said boss being enlarged radially outwardly of said outer surface and extending the width of said groove in said inner surface.

2. The shaft as claimed in claim 1 wherein said first-mentioned shaft is a hollow substantially tubular shaft.

3. The shaft as claimed in claim 1 wherein said first-mentioned shaft is hollow with said V-sahped groove in said first shaft extending along the entire length of said first-mentioned shaft, said boss forming said continuance of said first-mentioned shaft at one end thereof and a second boss on the outside surface of said first-mentioned shaft forming a continuance of that portion of said first-mentioned shaft including said groove at the other end thereof.

4. In an antenna rotator of the type'providing relative rotational movement between a shaft and a housing including the combination of a first shaft rotatably mounted to the housing and having an inner and outer surface adaptable to receive a second shaft adjacent to said inner surface of the first shaft, there being a clamping means in the form of a V-shaped bolt and a V-shaped retaining clamp at a point along the length of said first shaft to attach said first shaft to said second shaft, the improvement comprising,

said first shaft having a V-shaped groove extending in a straight line along the entire longitudinal dimension of that portion of said first shaft adaptable to receive said second shaft, and a boss forming an axial continuance of the outer surface of said first shaft and located at the clamping point, said boss having a groove transverse to said longitudinal dimension which is adapted to receive the V-shaped portion of said bolt so that the vertex of the V of said bolt is substantially on the same radius drawn from the center of said first shaft as the vertex of said V- shaped groove in said first shaft and the vertex of said V- shaped retaining clamp is opposed to the vertex of said V- shaped groove in said first shaft, said boss being enlarged radially outwardly of said outer surface and extending the 'width of said groove in said inner surface.

5. The combination as claimed in claim 4 wherein said first shaft is a hollow tubular shaft and said second shaft is a hollow tubular shaft.

6. The combination as claimed in claim 5, wherein a boss is located on both longitudinal extremities of said first shaft and each boss has a V-shaped groove transverse to said longitudinal dimension adapted to receive the V-shape of a bolt having a V-shape between parallel threaded ends. 

1. A shaft for improved securing thereto of a second round tubular shaft by means of at least one V-shaped clamp at a point along the longitudinal length of said first-mentioned shaft wherein the bolt of said clamp has a V-shape between its parallel threaded ends, said first-mentioned shaft having an inner and outer surface with said inner surface adapted to receive said second shaft, said first-mentioned shaft having a V-shaped groove in the inner surface thereof extending along the entire longitudinal dimension of said first-mentioned shaft, and further including a boss located at a clamping point on the outside surface thereof forming an axial continuance of that portion of said first-mentioned shaft having said groove, said boss having a groove transverse to said longitudinal dimension which is adapted to receive the V-shaped portion of said bolt, said boss being enlarged radially outwardly of said outer surface and extending the width of said groove in said inner surface.
 2. The shaft as claimed in claim 1 wherein said first-mentioned shaft is a hollow substantially tubular shaft.
 3. The shaft as claimed in claim 1 wherein said first-mentioned shaft is hollow with said V-sahped groove in said first shaft extending along the entire length of said first-mentioned shaft, said boss forming said continuance of said first-mentioned shaft at one end thereof and a second boss on the outside surface of said first-mentioned shaft forming a continuance of that portion of said first-mentioned shaft including said groove at the other end thereof.
 4. In an antenna rotator of the type providing relative rotational movement between a shaft and a housing including the combination of a first shaft rotatably mounted to the housing and having an inner and outer surface adaptable to receive a second shaft adjacent to said inner surface of the first shaft, there being a clamping means in the form of a V-shaped bolt and a V-shaped retaining clamp at a point along the length of said first shaft to attach said first shaft to said second shaft, the improvement comprising, said first shaft having a V-shaped groove extending in a straight line along the entire longitudinal dimension of that portion of said first shaft adaptable to receive said second shaft, and a boss forming an axial continuance of the outer surface of said first shaft and located at the clamping point, said boss having a groove transverse to said longitudinal dimension which is adapted to receive the V-shaped portion of said bolt so that the vertex of the V of said bolt is substantially on the same radius drawn from the center of said first shaft as the vertex of said V-shaped groove in said first shaft and the vertex of said V-shaped retaining clamp is opposed to the vertex of said V-shaped groove in said first shaft, said boss being enlarged radially outwardly Of said outer surface and extending the width of said groove in said inner surface.
 5. The combination as claimed in claim 4 wherein said first shaft is a hollow tubular shaft and said second shaft is a hollow tubular shaft.
 6. The combination as claimed in claim 5, wherein a boss is located on both longitudinal extremities of said first shaft and each boss has a V-shaped groove transverse to said longitudinal dimension adapted to receive the V-shape of a bolt having a V-shape between parallel threaded ends. 